Optimizing for IC10 single crystal Ni3Al-based alloy joint by electron beam welding with chemical composition controlling

Abstract

Due to severe cracking tendency in IC10 single crystal Ni3Al-base alloy jointed by electron beam welding, the solidification crack in the IC10 alloy weldment is detrimental for crucial applications in industry. In this paper, the cracking mechanism in the IC10 alloy joint was investigated, and a perfect joint without any crack is obtained by controlling chemical composition in weld, which microhardness is equivalent to the IC10 alloy and tensile strength is up to 900 MPa reaching 1.5 times of the IC10 alloy. The cracking initiation is derived from the liquid film of low melting point precipitated phase-Ta2C along grain boundary under welding stress during solidification. With chemical composition controlling that a 0.4 mm Inconel718 alloy layer is deposited by electron beam freeform fabrication on the welding path before welding, the finer high melting point NbC phases replacing Ta2C phases is precipitated along grain boundary, and the preferred orientation slender columnar grain containing with a multitude of deformation twins is formed in weld, which can reduce the number and proportion of high angle grain boundary, attributing to the elimination of solidification cracks and the enhancement of tensile strength.

Keywords

• IC10 superalloy
• Electron beam welding
• Chemical composition controlling
• Welding structural design
• Microstructure
• Mechanical properties